Steam boiler



Feb, 22, 1938.. K. c. SCHMIDT 2,109,278

STEAM BOILER Filed Sept. 25, 1936 5 Sheets-Sheet 1 Fig] 4% LIQL UL 1 65INVENTOR.

ATTORNEY.

K. C. SCHMIDT Feb.22, 1938.

STEAM BOILER 5$het kg e Filed Sept. 25, 1956 INVENTOR CO m. J@

K. C. SCHMIDT Feb. 22, 1938.

STEAM BOILER Filed Sept. 25, 1936 5 Sheets-Sheet 3 Q4 &

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Feb. 22, 1938. K. c, SCHMIDT 2,109,278

STEAM BO ILER Filed Sept. 25, 1936 5 Sheets-Sheet 4o0ooooooooooo-ooooooooooooooooooooooooioo000000000000000oooooooooooooooooooo 1 9. 9. 9 2 22.9 9..9 22.? 9.29.22 3.9 9 2.9.9-2222. 9.2.9.9. 9.512 9.2.2.41

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Kar] G. Schmidi Feb. 22, 1938. I K. c. SCHMIDT STEAM BOILER Filed Sept.25 1956 5 Sheets-Sheet 5 INVENTOR. Karl C 501721112125 KR WY.

Patented Feb. 22, .1938 i UNITED STATES PATENT OFFICE STEAM BOILER KarlC. Schmidt, Western Springs, Ill., assignor to The Babcock & WilcoxCompany, Newark, N. J., a corporation of New Jersey ApplicationSeptember 25, 1936, Serial No. 102,492

11 Claims. (01. 122336) I My present invention relates to the construc-18. The side wall 12 preferably includes hollow tion and operation ofsteam boilers of the water tile l2 arranged to form air passages openattube type and more particularly to steam boilers their lower ends.Extending upwardly along the adapted for installations having limitedhead opposite side walls are structural steel columns I9 room and floorspace available. In my prior which support girders 20 extending acrossand application, Serial No. 16,115, filed April13, 1935, I above the topof the setting.

a steam boiler adapted for such use is disclosed The interior of thesetting is' divided as herehaving a relatively large amount ofconvection inafter described into a relatively wide combusand radiantheat absorbing surface, furnace voltion lane or furnace chamber 2|. anda relatively ume, and length of heating gas travel in propornarrowlaterally adjoining heating lane or tube tion to the spaceoccupied andhead room rechamber 22. A pair of longitudinally disposed quired.parallel upper and lower drums 23 and 24 re- The main object of mypresent invention is spectively extend longitudinally and throughout theprovision of an improved furnace constructhe lengthof the heating laneand are connected tion for a steam boiler of the general typedethroughout their length by a bank of vertically l6 scribed in my priorapplication for adapting the disposed tubes 25 straight for most oftheir length same for stoker firing at relatively high efiland havingbent ends for radial connection into ciencies. A further object is theprovision of the drums at both sides of the central vertical means foreffecting an improved flow of heating planes thereof. The upper or steamand water gases over the convection heating surface. drum 23 is inwardlyoflset slightly from the lower The various features of novelty whichcharor water drum 24. The upper drum 23 is supacterize my invention arepointed out with parported from the structural steel members 20,inticularity in the claims annexed to and forming dicated in Fig. 1 ascarried by the members is, a part of this specification. For a betterunderand in turn supports the lower drum 24 through standing of theinvention, its operating advanthe tube bank 25. tages and specificobjects attained by its use, The heating lane 22 is separated from theadreference should be had to the-accompanying joining combustion lane 2|except at the rear end drawingsand descriptive matter in which I havethereof by a vertically disposed refractory partiillustrated anddescribed preferred embodiments tion 26 which extends between the drumsand terof my invention. minates at its rear end a substantial distance30 Of the drawings: from the rear wall II. The lower drum is ade- Fig. 1is a transverse vertical section of a steam quately protected along itsinner side by a reboiler constructed in accordance with my invenfractorycurb 21 on the floor l5 and by the tion taken on the line i-l of Fig. 2;thickened lower section of the partition 26. The Fig. 2 is alongitudinal vertical section taken on spaces between the outer side ofthe drums 23 and the line 2-2 of Fig. 1; 24 and the side wall i3 areclosed by refractory Fig. 3 is'a horizontal section taken on the linematerial so that heating gases entering the rear 33 of Fig. 2; end ofthe heating lane will be confined in the Fig. 4 is a view similar toFig. 2 of a modified space therein between the drums. A heatingconstruction; I as outlet or stack connection 28 controlled by 40 i Fig.5 is a view similar to Fig, 3 of the modi-. a damper 28 is provided atthe front end of the flcation shown in Fig. 4; heating lane. With thisarrangement heating- Fig. 6 is a view similar to Fig. 1 of the modigasesgenerated in the combustion lane will flow flcation shown in Figs. 4 and5; and longitudinally thereof, entering. the rear end of Fig. '7 is aview similar to Fig. 6 of a second the heating lane and passingforwardly therein modification. to the stack connection 28..

The steam boiler unit illustrated in Figs. 1 to The steam boilerillustrated is especially de- 3 comprises a setting or housingsubstantially signed for the burning of solid fuel in a bed inrectangular in horizontal. and vertical crossthe forward end of thecombustion lane. Asingle sections, and formed by a vertical front wallIt, retort underfeed stoker 30 is conventionally iiIusrear wall ll, sidewalls l2 and I3, inclined top trated in the forward half of thecombustion wall or roof I, and'bottom wall or floor 15. lane. The stokeris mounted on laterally, spaced The vertical walls of the setting areformed in walls 3| defining the sides of an air-chamber 32 general by anouter steel casing It, a layer of which is supplied by an externalforced draft fan insulating material I1, and a refractory lining 33.Solid fuel from a magazine 34 is fed by a suitable feeding mechanism 35into the stoker retort 36 from which it is forced outwardly over thestoker grates 31. Dumping grates 38 along the sides of the stoker permitthe fuel residue to be dropped into ash pits 39 along the sides of theair chamber 32 and from which. it is removed through suitable cleanoutdoors in the lower part of the front wall Ill.

The gas flow' area of the combustion lane is substantially restricted atthe rear end of the stoker by a transverse refractory dividing structure40 formed by a bridge wall 4|, wing walls 42, and an arch 43, whichunite to define a restricted throat or gas outlet 44 between the frontand rear sections of the combustion lane. With this structure thecombustible gas from the fuel bed and air as iyet uncombined will beintimately mixed by the high degree of turbulence on passing through thethroat into the rear section of the combustion lane and completecombustion in the combustion lane will be insured.

This throat divides the combustion lane into two parts, a forward parthaving the bed of solid fuel with which the air reacts to form completeand incomplete gaseous products of combustion with excess air, and arearward .part in which the combustible gas combines with some of theexcess air. The first stage of combustion in which the solid fuel reactswith air to form gaseous products requires a temperature as high aspossible consistent with ash clinkering limits, and

'the correct temperature is assured by a suitable ratio of hot to coldportions of its boundary walls. The second stage of combustion in whichthe last traces of combustible gas are burned in as little excess air aspossible may be advantageously carried out within walls that have alarger ratio of cold to hot boundary wall surface and the throat dividesthis section from the forward one.

A relatively large proportion of the heating surface of the unit isformed by tubes receiving radiant heat from the combustion lane. In thestoker section in front of the throat a row of tubes 50 extends upwardlyfrom the drum 24 at the combustion lane side of the partition 26. Spacedtubes 50 are connected directly to the upper drum 23, while theintermediate tubes 50 are L- shaped and have outwardly inclined legs 0extending across the upper part of the combustion lane to a header 5| atthe junction of the side wall I2 and top wall l4. The header 5| extendsthe full length of the unit andis advantageously supported bylongitudinally spaced hangers 52 from the structural steel members 20.The header 5| is connected to the upper drum 23 by a row of roof tubes53, which as shown, correspond in number to the tubes 50 and 50 Theouter side wall l2 of the stoker section is made of refractory with itsouter face air cooled by the hollow tile ducts I2. By proper selectionof the spacing of the water tubes 50 on one side wall, the tubes 50 overthe furnace and 53 along the roof, and of the area of the outer side andfront walls, the temperature of the stoker section in front of thethroat may be made as high as desirable.

At the rear side of the throat the header 5| is connected to the lowerdrum by L-shaped tubes 54 having outwardly inclined legs extendingacross the lower part of the combustion lane above the floor thereof andvertical legs extending along the outer side wall l2. Roof tubes 53connect the rear portion of the header to the upper drum. A cleanoutdoor 55 is provided in the rear wall II for removing ash deposited onthe floor of the combustion lane rear section. The ash deposited on thisfloor is protected against fusion by the horizontal legs of the tubesward of the throat, and the ratio of cold to hot area is larger than inthe section forward of the throat, and the value of the ratio may beselected by the spacing of the enclosing tubes.

The inner side of the rear section of the combustion lane is defined bya rear section 26 of the partition 26 which extends rearwardly from theinner wing wall 42 at a point offset towards the side wall l2.Additional rows of water tubes 25 are provided in the rear section atopposite sides of the partition section 25. These rows of tubes extendbeyond the rear end of the partition section and form a screen acrossthe entrance to the heating lane. The heating lane side of the innenwingwall- 42 and partition is cut away at an angle as indicated at 56 tofacilitate gas flow from the wide to the narrow part of the forwardlytapering heating lane; This construction substantially' contributes tothe maintenance of a .higher heat transfer rate as the gases becomecooler by increasing the mass velocity toward the outlet of the heatinglane.

With the described construction and arrangement, fuel is automaticallydelivered to and burned on the stoker at a rate suitable for the .loadand air supplied by the forced draft fan.

The gases generated flow rearwardly through the throat 44 into the rearsection where combustion is completed. The products of completecombustion or heating gases pass around the rear end of the partitionsection 26 and forwardly through the heating lane at a substantiallyincreasing mass velocity to the stack connection 28. To avoid by-passingof the lower portions of the water tubes at the front end of the heatinglane, baffle means are installed in that portion of the heating lane tocause'the heating gases to pass downwardly before leaving the heatinglane. As shown in Figs. 1 and 3, a two-section bafile is used having astationary upper section 60 and a vertically adjustable lower section6|. The lower section is carried by a guided rack 62 which can be raisedor lowered by a pinion 43 on a manually operable shaft 64.

Feed water is supplied to the front end of the upper drum or at anyother suitable point and flows downwardly through the forward portion ofthe tube bank to the lower drum. Most of the steam is generated inthetubes receiving radiant heat from the combustion lane and inthe tubes inthe rear portion of the heating lane. A steam outlet 65 is indicated atthe forward end of the upper drum.

In the modification shown in Figs. 4 to 6, the furnace chamber 2| andheating lane 22 are transposed so that the tube bank 25 is at theleftside of the unit. The construction is otherwise the same as the formshown in Figs. 1 to 3, except for \an alternate form of fuel burningstoker. In the modified unit, a horizontally arranged perforated plategrate 10 receives solid external fo'rced draft fan (not shown) through a75 The transverse duct 14 in the bottom part of the bridge wall 4| andseparate inlet openings I5 controlled by dampers 16. The air becomespreheated during its passage through the bridge wall duct, air chambertubes and tuyeres, and passes upwardly into the fuel bed on the grate ina multiplicity of small jets. The operation otherwise is the same as inthe construction shown in Figs. 1 to 3.

In Fig. 7 I have illustrated a four-drum boiler unit of the typedisclosed and claimed in my said prior application. The steam generatingwater tube surface is mainly concentrated in two spaced 'vertical banks25 and 25' respectively connected to upper and lower drums 23, 24 and23', 24. The furnace chamber in this form has its opposite sides androof partly defined by oppositely arranged rows of L-shaped tubes 50having their upper ends connected to the adjacent upper drum 23 or 23'.The fuel burning provisions shown in Figs. 4 to 6 are incorporated inthe modification shown in Fig. 7 as well as the bridge wall andpartition elements thereof. In Fig. 7 the heating gases generated divideat the rear end of the boiler between the two heating lanes at oppositesides thereof.

The steam boiler constructions illustrated are especially adapted forthe low capacity field heretofore substantially monopolized byhorizontal return tubular boilers. Although incorporating many featuresof modern central station design contributing to a high boilerefliciency, they can be used to advantage without a corresponding use ofother features.

I claim:

1. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane anda heatinglane laterally azfloining said combustion lane and containing said tubebank and communicating with said combustion lane at one end thereof, astoker at the opposite end of said combustion lane for burning solidfuel thereon and generating heating gases flowing longitudinally throughc said combustion lane and thence through said heating lane, and adividing wall structure including transversely spaced refractory wingedwalls arranged to provide a restricted outlet for the heating gases tothe remaining portion of said combustion lane.

2. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof, a stoker at the front end of said combustion lane for burningsolid fuel thereon and generating heating gases flowing rearwardlythrough said combustion'lane and thence through said heating lane,

and a dividing wall structure at the rear of said stoker includingtransversely spaced refractory wing walls and a connecting archconstructed to provide a restricted outlet for the heating gases to therear portion of said combustion lane.

3. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinalh extending'combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the'rearend thereof,a stoker at the front end of said combustion lane for burning solidfuel' thereon and generating heating gases flowing rearwardly throughsaid combustion lane and thence. through said heating lane, and adividing wall structure at the rear of said stoker including a bridgewall, spacedwing walls and an arch arranged to provide a centralrestricted outlet for the heating gases to the rear portion of saidcombustion lane.

4. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof, a stoker at the front end of said combustion lane for e laneand having their upper ends connected to said upper drum.

5. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a lon tudinally extending combustion lane and a. hea inglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof,a'stoker at the front end of said combustion lane for burning solid fuelthereon and generating heating gases flowing rearwardly through saidcombustion lane and thence through said heating lane, a dividing wallstructure at the rear end of said stoker constructed to provide-arestricted outlet for the heating gases to the rear portion of saidcombustion lane, a row of L-shaped water tubes extending upwardly alongthe inner sideof and across the upper portion of the front end of saidcombustion lane, a longitudinal header connected to said L-shaped tubes,and a row of roof tubes connecting said header to said upper drum.

6. A steam boiler "having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof, said means including a vertically disposed longitudinallyextending partitition separating said combustion and heating lanes andarranged to form a forwardly tapering heating lane, means for burningfuel in said combustion lane and generating heating gases flowingserially through said combusu tion and heating lanes, and a heating gasoutlet at the front end of said heating lane.

7. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communciating with said combustion lane at the rear endthereof, said means including a vertically disposed longitudinallyextending partition separating said combustion and heating lanes andhaving a rear section laterally ofiset relative to the forward sectionto form a forwardly tapering heating lane, means at the front end ofsaid combustion lane for burning fuel and generating heating gasesflowing rearwardly through said combustion lane and thence through saidheating lane, and a heating gas outlet at the front end of said heatinglane.

8. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof, means for burning fuel in said combustion lane and generatingheating gases flowing serially through said combustion and heatinglanes, a heating gas outlet at the front end of said heating lane, andvertically adjustable baiiie means arranged to effect a downward flow ofthe heating. gases adjacent said outlet.

9. A steam boiler' having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane at the rear endthereof, said means including a vertically disposed longitudinallyextending partition separating said combustion and heating lanes andarranged to form a forwardly tapering heating lane, means at the frontend of said combustion lane for burning fuel and generating heatinggases flowing rearwardly through said combustion lane and thence throughsaid heating lane, a heating gas outlet at the front end of said heatinglane, and vertically adJustable baffle means arranged to effect adownward flow of the heating gases adjacent said outlet.

10. A steam boiler having upper and lower drums, a bank of verticallydisposed water tubes extending between and connected to said drums,means forming a longitudinally extending combustion lane and a heatinglane laterally adjoining said combustion lane and containing said tubebank and communicating with said combustion lane, a stoker at one end ofsaid combustion lane for burning solid fuel thereon and generatingheating gases flowing longitudinally through said combustion lane andthence through said heating lane, a bridge wall structure at one end ofsaid stoker constructed to provide a restricted outlet for the heatinggases to the remaining portion of said combustion lane, separate airchambers below said stoker, a transverse passage through said. bridgewall, and damper-controlled openings separately connecting said-bridgewall passage to said air chamber.

11. A steam boiler having laterally spaced I pairs of upper and lowerdrums, a bank of vertically disposed water tubes extending between andconnected to each pair of said drums, means forming a longitudinallyextending central com-I bustion lane and a pair of heating laneslaterallyadjoining and at opposite sides of said combustion lane, eachheating lane containing one of said tube banks and communicating withsaid combustion lane at the rear end thereof, a stoker at the front endof said combustion lane for burning solid fuel thereon and generatingheat-.

